Genetic parameters and correlations for bioenergetic, biomass and chemical wood traits in Corymbia citriodora

Abstract

Corymbia citriodora (Hook.) K.D.Hill & L.A.S.Johnson is widely cultivated by small-scale foresters in Brazil due to its high growth rate and good wood quality, making it suitable for a wide range of commercial applications. This study aimed to estimate the variation, parameters and genetic correlations for bioenergetic, biomass and chemical wood traits in 18 open-pollinated C. citriodora families for 33-year-old trees, and to evaluate the possibility of simultaneous selection for multiple traits for different industrial applications. The wood traits measured were: extractives (EX), lignin (LI) and holocellulose (HO) contents, higher heating value (HHV), basic wood density (BWD), energy density (ED) and biomass (BI). Cluster analysis resulted in the formation of three distinct groups: cluster 1, comprising 12 families, mainly associated with lower BWD and BI; cluster 2, consisting of a single family associated with a higher EX and LI; and cluster 3, associated with higher BWD and BI. Narrow-sense heritability was low for most traits and moderate for BWD. Genetic correlations were significantly positive for the trait pairs EX×LI, EX×BWD, LI×BWD, BWD×ED, BWD×BI and ED×BI, and strongly negative for EX×HO and LI×HO. Genetic improvement for increasing cellulose production, based on direct selection for higher HO, will result in an indirect decrease in EX and LI. Breeding for charcoal production, based on direct selection for BWD, will result in an indirect increase in EX, LI, ED and BI. Superior individuals can be identified within the best families and selected for cloning in genetic improvement programmes, aiming to simultaneously increase wood quality for multiple traits and different industrial purposes.